Violet (Purple) Noise

Definition

Violet Noise

Violet noise is known as differentiated white noise, due to its being the result of the differentiation of a white noise signal. Violet noise generates very high energies at higher frequencies. Its power density is proportional to f^2 and increases by 6 dB per octave.

Violet noise is also referred to as purple noise. These names come from visible light that turns into these colors when a similar spectral distribution is applied.

In other words...

Violet noise generates a lot of energy in the highest frequencies: each octave packs as much energy as the four octaves below it!

Perception

White noise, which is spectrally flat, seems already very bright for our auditory system. Violet noise will sound even brighter with the midrange and bass frequencies totally missing.

Applications

In audio applications, violet noise represents a good candidate for dithering, a process in which noise is intentionally applied to a signal in order to randomize quantization errors during bit depth conversions. This process is referred as dithering or noise shaping

In healthcare applications, violet noise is sometimes used to mask tinnitus, a buzzing, ringing, or whistling in your ear, occurring without any stimulus.

Credits

Our violet noise sample file has been generated using wavTones' professional grade Noise Generator.

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